/Engine/Plugins/Developer/Concert/ConcertMain/Source/ConcertTransport/Public/IConcertEndpoint.h
Add an Event Handler
void InternalAddEventHandler ( const [FTopLevelAssetPath](API\Runtime\CoreUObject\UObject\FTopLevelAssetPath) & EventMessageType, const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [IConcertEventHandler](API\Plugins\ConcertTransport\IConcertEventHandler) > & Handler )